That axiom of Metaphysicians which is termed the principle of contradiction and which affirms that it is impossible for anything to possess a quality, and in the same time not to possess it, is a consequence of the fundamental law of thought, whose expression is x²=x.
George BooleRelated topics
anything axiom contradiction fundamental impossible law quality thoughtRelated quotes
There has been an inversion in the hierarchy of the two principles of antiquity, "Take care of yourself” and "Know yourself.” In Greco-Roman culture, knowledge of oneself appeared as the consequence of the care of the self. In the modern world, knowledge of oneself constitutes the fundamental principle.
Michel Foucault